KIEV, April 17 (Reuters) - Ukrainian national guard soldiers fired shots in the air when a crowd of pro-Russian separatists attacked their base near the eastern city of Mariupol on Wednesday, the interior ministry said in a statement.

A crowd of armed protesters arrived at the base and demanded that the national guard troops back their revolt against the country's new pro-Western government, the statement said.

When the crowd refused to disperse and tried to enter the base, the national guard troops shot into the air, the statement said.

It did not say whether anyone was injured in the attack.

Pro-Russian separatists have taken over buildings in at least 10 cities in Eastern Ukraine, attacks the Ukrainian government has said are orchestrated by Russian agents. The Mariupol city administration is already under the control of separatists.

Russia says the attacks are spontaneous protests by Russian speakers angry at the country's new government, which is more popular in the Ukrainian speaking west of the country. (Reporting by Conor Humphries)